A rotary type injection blow molding machine has four working stages consisting of an injection molding step, a temperature adjusting step, an orientation blowing step and a removing step as described in U.S. Pat. No. 4,105,391 Specification. These working stages are disposed at four locations of the machine bed, and a transfer plate provided at the under-side thereof with four lip molds corresponding to the working stages, respectively, is provided upwardly of the machine bed, so that when the transfer plate is rotated through 90.degree., an injection moled preform may be sequentially transported to the working stages, i.e., the temperature adjusting step and the orientation blowing step, and at the same time, a molded article such as a bottle which has orientation blow molded may be transported to the working stage, i.e. the removing step.
In such a molding machine as described above, the injection molding stage and the orientation blowing stage can be set opposedly each other on the machine bed in view of the order of steps, and the temperature adjusting stage can be set opposedly to the removing stage. Therefore, the arrangement of these working stages is extremely convenient in mounting devices necessary for molding on the rectangular machine bed, and the molding machine can be constructed compactly. Because the length of the machine bed can be utilized to place an injection apparatus thereon and a space for opening and closing a blow mold can be sufficiently secured. All the devices are well acccommodated on the machine bed.
The present inventor has previously accomplished the invention of the rotary type molding machine of the three-working stage with a temperature adjusting stage omitted (see U.S. Pat. No. 4,648,824). This three-working stage molding machine has the advantage in that when a preform is injection molded, an injection mold is utilized to effect the temperature adjustment of the preform, whereby the temperature adjusting device, devices incidental thereto and one lip mold may be omitted. However, the working stages, i.e., the injection molding step, the orientation blow molding step and the removing step are positioned at three locations of the machine bed, and therefore, if the injection molding stage is set in the central portion of the machine bed, the orientation blow molding stage together with the removing stage are obliquely positioned on the machine bed, and the opening and closing the blow mold, the replacement of the molds and the like are liable to be restricted as compared with the case of the four-working stage.
If the molding machine is small and the number of molded article to be taken is small, the blow mold is also small and the mold opening space need not be large and in addition, the weight is not so heavy, thus posing no particular problem. However, if two rows of cavity molds are provided into a larger size in order to increase the number of articles to be taken, the mold opening and closing, the replacement thereof and the like cannot be done smoothly merely by the restricted space on the machine bed, resulting in that an extension is to be provided on the side of the machine bed for these works.
Even if this extended portion is minor in view of the entire molding machine, it has to be removed for packing during transportation, and the installation space for the molding machine increases to constitute a trouble during the molding work, which is not desirable in use. If such a problem as noted above can be solved, even the molding machine of the three-working stage type can be used as a compact volume-production machine.
As the result of repeated researches, the present inventor has found that even in the three stage working stages, only the space on the machine bed can be utilized to smoothly carry out the molding opening and closing and also the replacement of molds.